Gear-finishing method



Feb. 12, 1952 M. B. MENTLEY 2,585,261

GEAR-FINISHING METHOD Filed Dec. 9, 1946 5 Sheets-Sheet l INVENTOR.

.MAX B. MENTLEY Feb. 12, 1352 M. B. MEN TLEY GEAR-FINISHING METHOD 5 Sheets-Sheet 2 Filed Dec. 9. 1946 INVENTOR.

MAX B.M ENTLEY ATTORNEYS Feb. 12, 1952 M. B. MENTLEY 2,535,263

GEAR-FINISHING METHOD Filed Dec. 9, 1946 5 Sheets-Sheet 5 INVENTOR.

MAX 8. MENTLEY M. B. MENTLEY GEAR Feb.12,1952

-FINISHING METHOD 5 Sheets-Sheet 4 Filed Dec. 9, 1946 INVENTOR.

MAX BMENTLEY ATTORNEYS M. B. MENTLEY GEAR-FINISHING METHOD Feb. 12, 1952 5 Sheets-Sheet 5 Filed Dec. 9. 1946 INVENTOR.

MAX B. MENTLEY s Y E N m W A Patented Feb. 12, 1952 UNITED STATES PATENT ()I' 'FI(IE GEAR-FINISHING METHOD.

Max B. Mentley, Detroit, Mich., assignor to Na-' tional Broach & Machine Company, Detroit, Mich., a corporation of Michigan Application December 9, 1946, Serial No. 714,925

2 Claims. 1

The present invention relatesto a gear finishing method and more particularly to one adapted to employ a rotary tool and work piece engaged at crossed axes which during operation of the machine are caused to partake of a relative traverse in a direction oblique to the axes of both work piece and cutter.

The present invention may conveniently be applied to a gear shaving machine of the type dis- .closed in the copending application Serial No.

694,590 filed September 3, 1946, entitled Gear Finishing Machine in which the applicant is Kenneth J. Davis and which is assigned to the assignee herein.

For purposes of completeness the description of the entire machine will be given, although the present invention is limited primarily to apparatus for effecting stoppage of the machine at a substantially invariable predetermined point of traverse so as to effect a gauging operation.

It is an object of the present invention to provide a method of the character described employ- I ing a rotary tool support and a rotary work support adapted to be associated at crossed axes and to partake of a relative traverse in a plane which is parallel to both axes and in a direction which is transverse to the axes of both gear and cutter, in which means are provided for effecting an automatic gauging operation by the simple expedient of loading an unfinished gear on the work spindle and manually testing for backlash.

Other objects and features of the invention will become apparent as the description proceeds, especially when taken in conjunction with the accompanying drawings, wherein:

Figure 1 is a front elevation of a machine tool constructed in accordance with the present invention;

Figure 2 is a side elevation of the machine tool shown in Figure 1;

Figure 3 is a fragmentary plan view of the work supporting mechanism as indicated by the line 3-3 of Figure 2;

Figure 4 is a section on the line 4-4 of Figure 3;

Figure 5 is a section on the line 5--5 of Figure 3; and

Figure 6 is a diagrammatic view of the cycle controlling mechanism employed in the machine.

Referring first to Figures 1 and 2, the machine tool comprises a main frame Ill having an over g the axis of the toolspinrile I 3 and preferably substantially centrally of the tool T carried thereby. A tool support of this general type is disclosed in patent to Robert S. Drummond, No. 2,270,421 dated January 20, 1942, and accordingly is not described in detail here. i

It will be noted, however, that independent motor means for effecting rotation of the tool spindle are provided as indicated at M.

The base of the frame l0 extends forwardly as indicated at l5 and'contains a'ifixed nut element (not shownlfor cooperation with an ad.- justment screw for effecting vertical adjustment of the work support, as will presently be described. i i

Mounted on ways 20 formed in a plate 2| secured to the upright portion of the frame It! is a knee 22. Means for effecting vertical adjustment of the knee, as best seen in Figure 5, comprises a vertically extending adjusting screw'25 which is mounted for rotation relative to the knee and at the same time locked against axial movement relative thereto by bearing means indicated generally at 21 (Figure 4). The upper end of the screw 26 is supported in bearings 28 and a bevel gear 29 is keyed thereto. Manual means indicated generally at 30 are provided for effecting rotation of the screw 26 and comprises a bevel gear 3| meshing with the bevel gear 29 carried by a shaft extending through bearing structure 32 and a closure plate 33 carried by the knee and terminating in a squared end indicated .at 34 for cooperation with a suitably formed tool.

It will be apparent that rotation of the shaft having the squared end 34 by a hand tool will effect .rotation of the screw 26, and that this rotation relative to the fixed feed nut previously described willresult in vertical adjustment of the knee 22. Mounted on the knee 22 for adjustment about a vertical axis thereon is a first sub-table 40 and means are provided for locking the sub-table 40 in adjusted position relative to the knee 22 which comprises a circular T slot 4| provided on the knee 22 and suitable locking bolts carried by the sub-table. and having head portions received within the bottom of the T slots 5 l. The first subtable 40 is provided at its upper surfacewith rectilinear ways 42 including a removable gib 43. A second sub-table 44 is shaped to cooperate with the ways 42 and gib 43 for rectilinear translation along the sub-table 40.

.Mounted for adjustment about a vertical axis on the top of the second sub-table 44 is a work table 45 and means are provided for locking the work table 15 to the second sub-table M which take the form of, a second circular T slot vMi 3 formed in the upper surface of the second subtable 44, suitable clamping bolts 46 being carried by the work table 45 for effecting locking of the work table in adjusted position.

The work table 45 is provided with rectilinear T slots 49 for adjustably receiving a headstock 4'! and tailstock 48. The headstock 47 and theitailstock 48 comprise means for supporting a rotary work piece indicated at W in Figure 1 in proximity to the location of the tool T. It will be observed from an inspection of Figurel that .in order to effect engagement between tool T .and the work W as illustrated it isnecessary to raise the knee by appropriate turning of the feed screw 26. It will also be apparent that in order to effect engagement between the tool and the work at crossed axes it is best to effect a desired rotation of the tool support l2 so as to bring the axis of the tool T into a desired crossed axial relationship with respect to the work without disturbing orientation of the work.

Referring now to Figures 4 and 5, means are provided for effecting relative traverse between the tool and work and more specifically for effecting translation of the work table45. This means comprises a motor '50 mounted on the knee 22 for vertical adjustment therewith'and having a drive shaft-| connected to a second shaft 52 by a coupling 53. The shaft 52 is supported in bearings indicated generally at 54 and terminates in a worm 55 which in turn drives a worm gear 56 (Figure 4). The gear 56 is mounted on a shaft 51 having a toothed driving portion-58 connected to oil pumping means indicated generally'at '59. Secured to the-oppositeend of the shaft 51 is a pinion'BO which drives a shaft 6i through an intermeshing gear 62. The shaft 5| carries a bevel gear 63 meshing with a. second bevel'gear carried by a vertical shaft'fifi'to which is keyed or otherwise secured a'gear 66. The gear 66 in turn meshes with a gear 61 keyed or otherwise secured to a shaft 68 at the upper end of which iskeyed or otherwise secured a bevel gear '69. The bevel gear 69 meshes with a bevel gear which. is keyed toa feed screw H which is mounted forrotation and held against axial translation relative to'the firstsub-table 40 by bearings indicated at 75 engaging opposite sides of. a supporting "shoulder structure 16.

The second sub-table 44 has rigidly "secured thereto in depending relation a. feed nut "which threadedly engages the feed screw H. Opposite ends of the feed screw H are provided with squared ends as indicated at 8% for suitable engagement by a hand tool for a'purpose'which will later appear.

From the foregoing description it will beapparent that rotation of the shaft 5! by the motor 50 results in rotation'of the feed screw 'H', and since this feed screw is held against'axial movement, itsrotation will result'in a timed traverse of the second sub-table 44 along the ways 42 previously described.

The circular T slot 4 I provided in the upper surface of the knee 22 is coaxial with the shaft 68 and accordingly rotation of the first sub-table 43 about this axis relative to the knee 22 may be effected without disturbing the train of gears interconnecting the motor 50 and the feedscrew H.

The circular T slot 46 formed in the upper surface of the second sub-table 44 has an axis parall'elto an axis of the shaft'BB and which coincides with the axis, of the shaft 68 When the sub-table 44 is in central position.

It is desired to change the direction of traverse of the work table in a horizontal plane without disturbing its orientation in order that long work pieces may be accommodated by the machine. Thus for example in the event that a gear to be finished is formed integrally on a long shaft the shaft may be mounted between centers or mounted in a special support adapted to receive intermediate portion of the shaft without giving rise to a problem of interference between the extending portion of the shaft and fixed portions of .themachine during the desired traverse. It is pointedout at this time that the traverse mechanism illustrated provides for the complete adjustment of the direction of traverse so that the work piece may be caused to move from its central position. in any direction through the complete arc of 360.

The gear 61 engages. a gear 12 which through suitable gearing indicated generally at 13 actuates timing means 14 for effecting control of the motors.

It will be observed that adjustment of the sub-tables 40 and 44 as a unit about a vertical axis will result in the rotation therewith of the feed screw H and the machine is so designed that either one end or the other of the feed screw H is always in-a position where it may be engaged by a suitable hand tool. This provides means for effecting a fine adjustment of the subtables relative to the machine, as will now be described. When the motor is stopped, due to the fact that the drive therefrom includes a worm and worm gear, the gear train connecting the motor and the feed screw H is effectively locked against a rotation initiated from the feed screw end thereof. Accordingly, when the feed screw H is rotated by hand it will result in rotation of the sub-tables 40 and 44 as a unit, this adjustment being effected by the bevel gear 10 meshing with the bevel gear 69, which at this time is effectively locked against rotation. It is recognized of course that rotation of the feed screw H besides effecting the desired angular adjustment of the sub-tables 4i] and 44 will also effect a very slight lateral displacement of the sub-table 44 with respect to the sub-table 40 due to the engagement between the feed screw ll and the feed nut 11. This movement is, however, inconsiderable and presents no difficulties.

In order that the work table 45 will be maintained substantially in its oriented position, linkage mechanism best illustrated in Figures 3, 4 and 5 is provided. As seen in these figures, the knee has formed thereon an upwardly extending plate to which are secured a pair of parallel movable links 86 which at their opposite ends are secured to a disc 81. A second pair of short links 88 'are pivoted to a shoulder 89 formed in a recess 90 formed adjacent the bottom of the work table 45. The disc 81 is freely movable within the recess except as its movements are controlled by links 86 and 88 and supported for such movement by a central screw 9| which bears on. a closure plug 92 closing the open bottom of the recess 90. As best seen in Figure 3, it will be apparent that the linkage thus referred to will maintain the work table 45 always in a substantially oriented position in its horizontal plane.

It is contemplated that in adjustment ofthe machine the feeding or traversing mechanism which comprises thefirst and second sub-tables 40 and 44 will be. adjusted to cause the ways 42 to extend in the desired direction of traverse 0f the work table. This adjustment of the subtables as a unit tends to rotate the work table '45 therewith, but such rotation is effectively prevented by the linkage mechanism referred to. After the adjustment of the traverse mechanism has been completed the bolts which extend into the circular T slots M and 46 are tightened,

thus locking the parts in adjusted position. Subtool spindle is positively driven and the work spindie is mounted for free rotation. Accordingly,

sequently thereto the tool supporting head .I2

may be adjusted about its own vertical axis of precise crossed axial relationship desired with respect to the axis of the work piece.

Referring now to Figure 6, the timing or cycle controlling mechanism comprises a dial IOI secured to the shaft I00, the dial preferably having suitable graduations as indicated at I02 to facilitate setting. These graduations may convenient ly be in inches and determine the length of stroke. The dial IOI is mounted in a recessed boss I05 formed on the main casting of the machine, and projecting inwardly from the boss I05 is a stop I06 whose function is to prevent im proper setting of the timing dogs I01 and I 08;. The dogs I01 and I08 are mounted for adjuste ment on the dial IOI, suitable securing means being indicated at I09 and H0, respectively. It will be appreciated that the dogs I01 and I 08 each have offset portions lying in different planes of rotation which are respectively adapted to actuate one or the other of the two switches.

Mounted on the frame of the machine adjacent the boss I05 is a safety limit switch H2 and a stopping and reversing switch H3. The safety switch II2 has a plunger [I4 which is adapted to be actuated by a bell crank lever I I5 mounted for rocking movement about a pivot pin H6. The bell crank H5 is supported in inoperative position against an adjustable set screw II! mounted in a projection II8 formed on the frame of the machine. At one end the bell crank H5 has an adjustable actuating bolt I which is threaded through an opening adjacent the end of the bell crank and retained in adjusted position by a lock nut I2I. The other end of the bell crank II5 carries a roller I which is adapted to be engaged by one of the dogs I0! or I08 in the event that the stopping and reversing switch I I3 fails to operate.

The stopping and reversing switch II3 has a lever I provided therewith as indicated at I3I and carries at its free end a roller I32 adapted to be engaged by dogs I01 and I08. The dogs I01 and I08 have surfaces respectively adapted to engage the roller I32, and other surfaces adapted to engage the roller I25 shortly thereafter in the event of failure of the reversing switch I !3. The circuit for the motor 5 0 includes the switches II2 and I I3, and the switch I i3 has associated therewith a suitable plugging relay for the purpose of arresting rotation of the motor immediately upon actuation of the switch I I3 to stop the motor upon termination of a cycle. The cycle for this particular machine involves a single back-andforth reciprocation of the slides to effect two relative traverses between the gear and cutter. By

employing the plugging relay referred to, the

when a new work piece is located on its spindle'in mesh with the gear-like cutter carried by the tool spindle, a predetermined amount of backlash will be present depending first upon the position of the dog I0! which determines the stopping point of the work support, and second upon the dimensions of the rough gear to be finished.

It will be recalled that the present machine is particularly well adapted to take a very heavy cut and to complete a rough gear in a single backand-forth traverse. However, in the event that one or more oversize gears is present in a group being processed, severe damage could be caused to the machine by initiating its operation. Inaccordance with the present invention the operator can determine immediately whether or not each gear which he places upon the work spindle is within safe limits by the simple expedient of testing it by hand for backlash, and if less than the usual or a minimum amount of backlash is present it will be apparent immediately that the gear is oversize and should be subjected to further roughing operations before-being finished on the shaving machine.

This means of gauging for oversize gears is possible with the present machine due to the fact that the machine is normally operated with a direction of traverse forming a very substantial angle with the axes of both gear and cutter so that upon completion of the cutting part of a stroke a very limited additional traverse moves the gear and cutter to very substantial backlash without moving the parts out of mesh. It is thus possible to employ this predetermined amount of backlash resulting from a small additional amount of relative traverse as a gauging means without introducing a serious loss of time in the cycle. Furthermore, the present machine is adapted to finish gears without a feeding movement reducing the normal spacing of tool and work axes, so that this spacing, which enters into the provision of constant backlash at end of cycle, is invariable for a sequence of like gears.

While the present invention has been illus trated and described in conjunction with a par-- ticular gear shaving machine, it will be appreciated that this has been done merely to enable those skilled in the art to practice the invention, which is applicable to a wide variety of gear finishing machines and is not to be construed as limited to the particular machine illustrated and described herein. The true scope of the invention is indicated in the appended claims.

What I claim as my invention is:

1. The method of initially gauging and then finishing a series of gears by rotating them in mesh at crossed axes with a gear-like finishing tool which comprises providing a pair of supports for said gear and tool in definitely spaced relation representing a predetermined backlash between the tool and a gear of proper size for machining, one of said supports having a tool thereon, mounting a succession of gears on said other support, testing the gears for backlash, removing any gears which are dangerously oversize, effecting relative back-and-forth traverse between gears of proper size and the tool in a direction which occupies a plane parallel to the axes of said gear and tool, which direction is oblique to the axes of both gear and tool while rotating the gear and tool in mesh, and arresting said traverse with said supports in the relative position representing said predetermined backlash.

.32.:l2hezmethod of initially jgauging and then .finishing-aseries of gears by rotating them in lmeshtat crossed axes with a gear-like finishing tool-whicheomprises adjusting a rotary tool support and a rotary work support in crossing rela- .tionship and to a normal spacing proper to machine-work gears-carried by the work support to aipredetermined size by a gear-like tool carried by the tool support, relatively adjusting said supportsin traverse in a plane parallel to the axes oi :both of said supports to a loading position which provides a small amount of backlash between the tool and an unfinished work gear of dimensions suitable for finishing, placing unfinished work gears on the work support serially, testing for oversize gears by checking backlash manually by relativelyrotating each meshed gear and tool, re- .moving oversized gears, finishing proper size gears bydrivingone support in rotation, thereby driving the other support through the meshed en ,gagement of gear and tool, effecting one or more complete back-and-forth traverse strokes between 'said supports in a direction which occupies a plane parallel .to ;.the axes of the supports and which .directionis oblique to theaxes of both supports,

and terminating each traverse sequence accurately in the predeterminedloading position to provide ,for a'backlash check of the succeeding work gear.

MAX B. .MEN'I'LEY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,270,421 Drummond Jan. 20, 1942 2,335,215 Schurr Nov. 23, 1943 2,350,882 Drummond s June 6, 1944 2,380,208 Ashton July 10, 1945 2,435,405 Praeg Feb. 3, ,1948

FOREIGN PATENTS Number Country Date 480,247 Great Britain. Feb. 14, 1938 

